Traffic signal



Sept. 24, 1935'. c. ADLER, JR ,0

TRAFFIC SIGNAL i Filed Jan. 13, 19:52 I s Sheets-Sheet 1 Patented Sept.24, 1935 UNITED STATES OFFICE l v 2,015,612 1 g 'raamo SIGNAL Y CharlesAdler, In, Baltimore, 4 v ApplicationJanuary 13,1932, Serial No. 535420'zolrin'm...(o1.1-1-1--,s: x-nl vv The present invention relates totrafllc signal started but is incompleted, the sounds created j systems,and more particularly comprises an im-' by the succeeding vehicle'willhalt suchtransfer provement upon signals of that character which untilthe sound vibrations "are no ,longer sum are generally spoken of astraflic actuated. ciently intense to be received by the means at- 5 Inthe present case I employ a trailic actuated the intersection when thetransfer will be conmeans, namelyasound box, which is arranged in.ti'nued.-, e the highwaysin advanc'eof the intersection which It is afurther object'of the invention to proit is desired to control.Cooperating with such vide a mechanism wherein continuous subsequenttrafllc actuatedmeans, but independent thereof, j actuation ofthesame'trafllc element in any one I 'are means arranged at the.intersection 'which road will have no effect upon the 'mechanismqo aredirectly sensitiveto sound waves created'by for transferring right(if-way. a. t v the passage of vehicles. It is therefore the pri- I Anadditional object of the. invention is to; mary object of the inventionto provide a traffic provide l mp ir ui *w y' the, sisnal-jwill controlsystem wherein the conditions prevailing operate'on the split amberpri'nciplef n n Y at the intersection will govern the transfer of Afurtherobject ofthe inventionis topro- 5 the stop and go indication backand forth; In vide a signal system which can be msqemn other words, thetransfer in accordance with automatic, orcaus'ed to asareverting'isignalthe present system will 'talr'epla'ce substantially without changing thernecl anisrn'; I instantaneously with the actuation of the traffic I Itis, however, the prime purpose-of this in:

actuated element, but by reason of the' means at vention to avoid theuse of any timing m en= the intersection, such immediate v transfer willanism and the signal whichhasno normal is f be prevented or halted atany point, i'. e.', sub-i completely controlled by name,beinggcharacter; ordinated between the movement of the signal ized y fred mfromany so-called minimum or mechanism to present stop and 'go; j m man avl 'aln immediate operable It will therefore, be seen that thepresent ins u d actuat d sisnalchansing means subordi 25 vention seeksto eliminate, and does eliminate, an d; h w veri t0 asparately.operablecontrol timing such as has been heretofore practicedinmeans which is superior "to said first named connection'with traihcactuated systems. There ans, fl y, t in ep nden 8nd is no maximum orminimum period for the parperior control is also sound actuated;

iticular signal indications as understood in the "Referring to t d awngs, I have illustrated in v art, and in fact the signal indicationswhen no F SI 1 a i a O my System, and in Figurez,x traffic is present,are transferred immediately a f her dla ram ofa modification.

upon actuation'of the trafllc actuated element, F r s 3' and 4 aredetailviews ofthe' name and where tr'aflic is present and sound wavesare flctuatlednelements} I n being created at the intersection,suchsound I v illustreted'the invention nnl 't an 35,

waves control the transfer, i. e.," are superior intersectionhfiv'ingfih nve s ng oadways A and-there'is no definite time period foreither nd Preferably i hf w ys I road leading to the intersection. placea traffic actuated element'which is disposed The present invention ispracticable because in ad n the intersection; These n me 5 40 -it hasoften been observed that vehicles apmated elements ll d eas lfand 2 'inproach the intersection in a stream and as long street A, and 3 and l instreet B. They wmw e as such vehicles are sufficiently close together,re sp fi y 'hereflf erlbut in the the soundvibrations created by themwill pre- Present instance comprise elongated hollow sealed vent anytransfer of the signal to the other road. boxes 1 re p s w h interposedi the? When, however, a gap occurs in the vehicle street .with theirtopsurfaoes'ilush therewith, and 45 stream, as experience indicates is theusual conh associated microphones w e y the lvib'ra dition of movingtraffic, an actuation of the-traflic t n created y v hicles moving overthe hollow; element onthe other; intersection will instantly box w l b tan to h? is c em mtransfer the signal and halt'traillc in the line of eso d bo e an 2 areeormected by a wire the trafllc stream.- 5 to eachother andare connected in series by the 50 Asa condition, however, tosuch a transfer, wires 6; and 'l with the primary of a transformer ifthe gap is not sufficiently large, or if the A ryfl1Sin 1l Sdinthelinetothe'p flsounds created by the succeeding vehicle aresuilimary. The elements I and A are similarly conciently intense,actuation of the traffic element nected to the'prlmary of a transformer'll; The will not causea transfer, or if the transfer has 1 secondary ormicrophonecircuit includes the sec- 55 the usual electromagnet I 3 andarmature l4. The

armature I4 is connected by a wire II! to a battery or other source ofdirect current 18. The armature also rests at its other end upon acontact II which leads by a wire I8 to a contact member l8 associatedwith a relay 28 comprising the usual electromagnet 2| and armature 22.There is also connected to the battery by the wire 23 through contact82a second, armature 24 which is associated with the armature 22 andelectromagnet 2! of relay 28. The armature 24 is connected by a wire 25to a second armature 28 which is 'connectedthrough contact 82' to a wire21 leading to an electromagnet 28. This electromagnet 28 is associatedwith a brake mechanism comprising an armature 28 mounted at the end 01'a pivoted arm 38 from which armature extends a leg 8i carrying a stoplever 32.- The stop lever 32 has an upstanding brake shoe 33, and at oneend is provided with a tapered foot 34. The electromagnet 28 is normallyenergized and thereiore supports the trip lever 32 in elevated position.

The braking mechanism just described is adapted to engage a disc 35which is rotated by means of an induction motor 36. The induction motoris wired to a source of alternating current through the wire 31 and isalso connected by a 88 to the armature 39 of a relay 40 having anelectromagnet 4|, which armature is normally nected by a train ofgearing 41 to a shaft 48' carrying insulated contact arms 49 and 50,thecontact arm 58 extending beyond the varm 48. Both arms 48 and 58 areconnected through leads 83-84 to battery l8 atall times.

The contact 5|) is adapted to engage respectively thecontacts 5|. and52, which are diametrically disposed about the path of rotary movementof such contacts. The contact segment 52 is connected by a wire 53 witha relay 54 comprising an electromagnet 55 and an armature 56. when thecontact 58 is in engagement with the segment 52, it will energize themagnet 55 and lift the armature 55 to engage, a contact 51 leadingto theamber light 58 on road B. When the contact 58 engages the segment 5|,the relay 58 comprising electromagnet 68 is energized to attract thearmature 8| to engage the contact 52 which leads to the amber light 53on road A. The contact 48 engages a'circular contact surface which isdivided into segments a and b defined by the diametrically disposedinsulated points 64. When the contact 48 engages the segment b, as shownin the drawings, the relay 65 has its electromagnet 66 energized toattract the armature 61 into engagement with contact 68, which leads tothe green light 69 on road B. The red indication 18 on road A is inmultiple with the circuit to the green light 88 and consequently whenthe green on road B is illuminated, the red on road A will likewise beilluminated. When the contact 49 engages the contact segment a, theelectromagnet 65 is deenergized and the armature 61 drops intoengagement with contact 1| which is connected to the green light 12 onroad A and, as shown, the red light 13 on road B is in multiple with thecircuit to green light 12 so that illumination of green light 12 on roadA will simultaneously illuminate red light 13 on road 13.

It is to be observed that by reason of the position of the amber segment52, coinciding as it does with a portion of segment b, that in the atransfer from road B to road A, the respective contacts 48 and 50 willengage respectively the contactv segment 22 and the amber segment 52.Thus in transferring right at way mm road B, there will appear with thegreenon road B also an amber indication since the lights 58 and 69 willboth be illuminated.' At the same time, however, the red light 18 onroad A will remain illuminated until the contact 48 engages the contactsegment a when the amber and green on road B will be 15 extinguished andsimultaneously red will appear on road B and green on road A.

As stated, the induction motor-circuit is normally made through wire 31from the source of alternating current and wire 88 leading to armature38 and ground. The relay 48 is associated with a microphone 15 having amegaphone 16- associated therewith, one side of the microphone circuitbeing suitably grounded, as at 11, and the other side leading by a wire13 to the battery I8. In the line 18 is a resistance 18 forming aprimary transformer coil cooperating with a secondary coil 88 having itsterminals connected with th eiectromagnet 4|.

The operation of the invention will now be described, and it is to beobserved that with the diagram shown in Figure Lthe'green light 69 andthe red light 10 are illuminated, the contact 48. engaging the contactsegment I), and hence the. signal is set to move traflic along road B,and halt traflic on road A.

Upon avehicle passing from one of the traflic actuated elements I- or 2,'or both oi them, an alternating E. M. F. is set up in the secondary, lloi the circuit to relay l2, which attracts the arma 4 ture l4 and breaksthe circuit from the battery through this armature and wire l8 toelectromag-' net 2!. The electromagnet being thus de-energized, permitsthe armature 22 to drop from the; contact i8 and the armature 24 to dropfrom the contact 82. The armatures 22 and 24 are mechanically associatedwiththe relay 20 and simultaneously operated thereby. I

When the armature 24 drops, the circuit from' the battery through thewire 28 tothe contact 0 82 is broken, and hence the circuit from thebat-- tery through wire 21 to' electromagnet 28 is broken, de-energizingthis electromagnet and permitting the trip lever to drop out of engagement with the pin 48. Since the motor 35 15 constantly energized and isonly restrained by the brake shoe 33, it will at once through the gear43, disc 44 and associated gearing, act to revolve the shaft 48. As theshaft 48 revolves, the contacts 49 and move toward the insulated 00points 64 and the-split amber indication is given on road B with thegreen and amber. lights energized due to. engagement of contact members48 and 50 with segment I) and amber segment 52.

As the insulated contact arms are rotated, and 85 pass into contact withsegment a, the green light on road A is illuminated and the red light onroad B likewise illuminated. At the same time,

a circuit is established through wire 83 which is connected to thecontact members 49 and. 50 and battery l6 through wire 84, on the onehand, and wire 85 which is connected to the contact segment a, and torelay 2D and its ground on the other hand. This circuit will energizethe electromagnet 2! as soon as contact 49 engages conengage theperiphery of the disc 35 and stop further rotation of the parts. Hencethe signal will havebeen transferred toroad A.

, It will be understood, of course, that as soon as vibrations createdby passage of a vehicle over the sound elements I and 2 cease, thearmature II will drop into engagement'with contact I1 and the circuitwill be re-established. In this connection, it will be noted that withthe signal now set for go on road A, the'passage vehicles over the soundelements in road A will not circuit is now made through t produce anytransfer movement, forwhile the armature H will'jiggle due to thevibrations set up by the sound elements i and 2, the circuit to therelay 2!! is independent t reof since said contact segment a, andtherefore armature 24 -will not drop. Hence a stream of vehicles maycontinue to pass over road A without ,ail'ecting the signal unless oneof the sound actuatedfelements 3 or on roadBis actuated.

The purpose of the microphone and associated circuit will now bedescribed. At this point, however, it should be stated that the disc andthe associated mechanism whereby the shaft 48 is operated, are simplyactuating means and have for trafllc purposesno' timing value. Thusactuation of either of the sound actuated members i, 2, 3, and lwill'cause a sub-' stantially immediate transfer of the signal back andforth between the roadways, and whatever a time period may be requiredto effect such transintersecting highways.

ground at the intersection Also, I may'use a single microphonepositioned in the box or housin: for the signal mechanism which isdisposed 5 at the intersection. Again, where a centrally disposed signalbox is employed, that is, one situated on an island in the center of theintersectiom'I may place one or more microphones in the proper positionsons to be exposed to travelling on both The sensitivity of themicrophone may iusted and controlled by a suitable regulable resistance90, asshown.

' vAs set forth, the normal circuit to the induction'motorjt is madethrough the armature which is grounded at 42. However, assuming thatvehicles are passing cm road A, they willset up sound vibrations, as forexample those created by the motor, as well as any incident to thecharacter and condition of the machine, which vibrations will be caughtby the microphone It to induce an alternating E. M. F. into thesecondary ll to energize the electromagnet 4i and attract the armatureto thereby break the circuit to the motor 36.

I will now describe the conditions under which v The present signal inaddition permits the the'micro'phone 15 operates to render the trafljlcsignal efficient.

In the-first problem, where traflic is light on both streets, if the "gosignal is onroad is, ac-

The second problem is where a stream of trame is passing on road Aand'tramc desires to cross "road B. In this situation, as long'asvibrations are set up at the intersection-to which i0.

phone is sensitive, actuation 'of'the' elements 3 and l, is subordinate,and'while'it break the circuit and de-energize thebr'ake magnet 20, cannot cause a transfer since the 1 motor circuit through armature thebroken because the armail;

ture 38 will be attracted bythe electromagnet 4i and hence microphone Ill and associated mechanism is superior. 'Iherefore,'the-signal will nottransfer until the sounds eitherceaseor microphone.

With this conditionin trafllc engineers have observed from experiencethat in trafllc streams there'is usually, a gap,'and hence if one,

tuatlon of "elements i and 2 will immediat transfer it to road A, viceare of less intensity than sensitivity of the-l0; I

of elements 8 or 4 have been actuatedfwhenu this gap occurs the sound"vibrations either cease or become of decreased-intensity, the armature39 will drop and the motorligwill' operate to transfer-right'of way. ofthefact that the actuating mechanism comprising the- '30;

disc 35 associated parts to the shaft 49 move too rapidly to haveanytrafllc cone trol value, advantage can be taken of the gap totransfer the signal without dimculty;

However, it is necessary to safeguard sunburn- 35- mediate transfer aswhere the gap-betweenthe vehicles is relatively short, and hence wheresuch a short opening in the trailicstream exists, the vibrations setupby the succeeding vehicle 612- flningthe gap will be" at once .pickedup by the 40 I microphone to lift thearmature 39 and stop the operationof the motor,and hence the transfer of the signal. Thus such transfermay bev halted,

. i. e., is subordinated atany point in therotating movement of theshaft 48 to the action of the, superior'microphone circuit. Asga result,trafllc waiting to cross the intersection must wait until another gapoccurs-inthe stream on road A, when the armature will drop'and the motorwillcontinue to operate the parts.

, Of course, the same result 5 is a stream of traffic. on road 13 andeitherof the 7 or sound waves, or such sound waves-as are present arenot sumciently intense to be picked upby the microphone.. r

transfer-to be interrupted at any point in the Lrotation of the shaft48, with the result that the transfer although released may be retardedwhena I ever the sound-vibrationsare suchas will be Y picked up by themicrophone. As theresult, there f7 is no definite timeperiod for therotation of the shaft inresponse to anactuationof the Mo elements.

In some cases there is a natural tendency of the I l' disc V3! to coastslightly,-which wmact to move" the shaft in the direction. of transfer,and of course the vibrations may be such that the armature 88 willjiggle to intermittently move the shaft 48 in the direction of,transfer.

It is these important characteristics of the present invention whichmakeit as near to the presence of a trafllcoflicer as it is possible fora machine to be.

The present invention can be made into an m. automatic reverting signalindependent of the sound means by interposing a manual switch 88 I inthe lead II or the lead M which switch when thrown open will render thesound means I, 2, 3, 4 and 18, I8 ineffective.

u. In this manner, if it is desired to have the signal indicationnormally green on road A and the mechanism operable to transfer to greenon road B, the switch 88 in lead 8| will be opened and permitted toremain so. Thereupon, when {9 the sound elements 8 or 4 on road B areactuated, relay I2 attracts the armature I4 and breaks the circuitthrough lead H to relay 28', whereupon armatures 22' and 26 drop and theelectromagnet 28 is de-energized. The brakelever then 2| :dropsiand-theshaft 48 rotates to transfer the signal to road B. Electromagnet 85being thus energized by connection to the contact segment b attracts notonly the armature but also the armature 86, establishinga circuit fromthe.

30 battery I8 through lead 84, armature 88, lead-8l to the relay 28',thereby attracting the armatures 22' and 28.

In the normal operationof the invention with both switches 85 closed,this would re -establish the as circuit through the line from battery I8and leads i8--8224-25282l to energize. solenoid 88 raising brake lever82 and fix thesignal for road B as shown in the drawings, the operationof the parts for'each road being the same.

However, with switch 85 in lead 8I open, such circuit cannot beestablished except when contact 48 engages segment a, since armature 24only contacts with contact 82 when relay 28 is energized, and the latteris only energized when green'is given on road A, i. e., through batteryII, lead 84, 88, contact 48, segment a, lead 85 to relay 28.

'Thus the contact arm 49 will, in the absence of actuation of relay 48through sound vibrations 0 which, like the other sound actuated means,is rendered ineffective, continuously move over thesegment I), andreturn the signal to road A when the circuit above mentioned will becompleted and solenoid 28 energized. g5 The speed at which the disc 35rotates will be such that notwithstanding it must make a completerevolution to return the green or right of way to road A in the vehicleoperated reverting type of signal in accordance with this invention, 50the time period will not be comparable to that now permitted or requiredin normal traflic operation. Dependence is therefore placed upon thesuperior microphone system I5 disposed adjacent the intersection which,in accordance with the 55- sound waves or vibrations created by thepassage of moving vehicles, will control the transfer of the signalindication. Hence it will be seen that in this vehicle actuatedreverting signal no predetermined minimum or maximum time periods 70tare possible and the transfer is solely regulable by the continuity ofthe sound waves and their intensity relative to the microphone. system.In other words, the vehicle actuated reverting system has no compellablefeatures such as under- 75 I stood in the art. Thus the signal will notchange to give the green to road B as long as the sound waves at theintersection are such as to maintain the electromagnet 4| energizedandhence there is nothing resembling a predetermined maximum.

Similarly if the brake lever has been released by 5 actuation on road B,the rate of transfer can be interrupted and delayed in accordance withthe sound waves at the, intersection again excluding the uselof anypredetermined maximum. when the signal indication has been given to roadB it will remain on road B only as long as the intensity of the soundwaves causes energizetion of electromagnet H in the event of actuationof eitherthe element I or 2 in row A. Hence,

there is no condition resembling the so-called minimum. When it startsto revert, this reversion may be halted or delayed as the conditions atthe intersection, namely the intensity of the vibrations or sound waves,require.

The invention is capable of acting as a full automatic signal by openingboth of the switches 85 and then changing the gear ratio between themotor and. shaft 48 to produce an appropriate timing, in which eventsolenoid 28 can never be energized.

' signal operation.

It will be understood that the ratio of the gearing between the disc44and the shaft 48 is such that the arm carrying the contacts 48 and 88will rotate at the same speed as the disc 44. This may be varied, ifdesired, but it is preferred that they have the same speed of rotation.

Referring to Figure 2, I have illustrated a construction which issubstantially similar to that shown in Figure l, but in which a motor,pref- 5, erably a series motor I88, drives the shaft 48 to rotate thecontact members 48 and88.

The signal being set for go on road B, it is to be observed thatactuation of either of the traflic actuated elements I, 2, will causethe ar- '56 mature ml of relay I82 to be attracted, thereby breaking thecircuit from the battery to the electromagnet I88 of relay I84. Thiswill deenergize the electromagnetand permit the armature I85 thereof andarmature I88 which is mechanically connected with armature I88, to drop.Armature I88 will engage the contact I8'I which leads to the armatureI88 of microphone relay I88. Armature I88 is electrically connected withthe motor through lead II8. Thus the circuit to to the motor includesthe source of alternating current, armature I86, and the circuit justdescribed. The control of the motor is obtained in the same .manner asheretofore described in connection with the microphone 18. Since theinsulated an for example byimposing gearing between"the motor and shaft48. t v

In the illustration' givenin-Figure 2','the green light on road B isoperatingfbut the transfer of right of way is substantially similar tothat setforth in connection with Figure l. As with theconstruction shownin Figure l,- the mechanism which is operated by'actuation of therespective sound elements for the respective streets 1d of theintersectionis similar, and'I have therefore simply described theoperation oi the apparatus as far-as possible to effect transfer ofright of way from road B to road A; it being understood that thecircuits to the lamps are identical with the prior describedarrangement;

In connection with the construction of Figure 2, it will be understoodthat the motor will-stop whenever the contact 40 engages either'of thesegments a' or I), this being due to the circuits established on theone'hand through 'line 'III' to relay II2, whereby the circuit fromthebattery through line 3, armature H4 and line II5 to relay I04 iscompleted, breaking the contact between armature I06 and contact I0'I.In the same manner, when the contact 40. engages the segment a, themotorcir'cuit is broken by reason "of the energization of relay I04through the medium of line I I6 and line I I 3 leading from the bat-.tery through line I II to the contactor and lifting relayI06.

' Referring to Figure 1, and providing there are no sound wavesatthe'intersection such as would afi'ect'the relay 40, movement over oneof the sound boxes in one highway will startthe trans- 051 ferring ofthe signal, and ifimmediately there-.

after the sound box in the other int'ersectingroad be actuated, thebrake will not be applied.

will be'cle'ar, since if the element 2 be actuated,

cent pin or 46, element3 be operated, the siga up nal will return togive right of way" to road B.

This-is due to the fact that while armature 24 may be picked up when thecontact 49 is on segment a, armature 26 cannot be picked up until thecontact 48 is on segment b, and consequently the electromagnet 28 willremain de-energized.

Of course, this transfer of right of way in accordance with my inventionwill be too rapid for practical traffic regulation, and in actualoperation the microphone 15 will pick up vibrations 55 from the firstcar and delay or retard the return of the signal to road B since theinduction motor will at least, if there be only a single car crossingroad A, be halted or stopped for suflicient time to properly control theintersection and prevent 00 any dangerous result. As will be observed,the

signal is operated by independent sound actuated means, (onesubordinate, namely the. transferring means, actuated by elements I, 2,3, and 4, and the other superior, namely the microphone 1'06 control"I5-394I) and is free from any minimum or maximum timing. Furthermore,the signal does not require anynormal.

It will be understood that a single microphone 15 may be employed, andwhere I employ two or more microphones, whether they be positioned atthe comers of the intersection or on an island in the center, I preferto connect them in series.

In the drawings, I have indicated the batteries by the numerals D. C.,and the source of operating current for the motor as A. 0., although itwill be understood current-can em.-

playedwhere available.

" The construction shown Figure may be.

adapted for a reverting signal or fullautomatic signal by interposingswitches similar to those *5 of Figure-1 and changing the gear ratiobetween the motor and shaft 4a- Innormal operatiomno timing isprovidedfor, the signal being solely responsive to conditions at theintersectiongand in the absence of soundsor m vibrations at theintersection, the j'actuating means has no trafilc control value. :Inthis; man-' ner; I obviate the use of such objections .as; timeextension, since nominimum or maximum ispro- M vided forinnormalop'eration and transfer being 16' solely under control ofmicrophone. I5. is; ;-in-

The microphone-or. microphones maybe sensitive to vibrations,soundiwaves, orboth, and ad-.

justed' to pick up and handleall character of con- 20.

ditions prevailing at the .intersection;. When used as a revertingsignaLtmmc elementsin one" street; will notbe necessarmeswlllbe-understood- 0 Referring toFigures 3 the construction 2 5 and 4will..-be.explained.-

. .1 Each" of these elements makes use of .an outer shell comprisingabottom' I22;.'-two side-walls I20 and two end walls I24 and I25. Thisshell, in practice, isof a rectangular-shape and-is. about five feet teninches long, more'or less; about-ten or-eleveninchesin width and between'nineand of the sound-producinghighway elements ,Ij;.2,; l,

ten inches in heightmIn practice, this shell is 1 embedded in-the'highway.

I "A-cover l26 is-providedover thetop of the 1 hollow shell andfromtheunder side of this cover there'depends an inner shell I21. "Thisinner shell is formed of metal that is very much thinner than that ofthe outer shell: and isclosed'at the 40- bottom, sides,-one end and ofcourse at the top,

because its upper edges} are preferablyi'welded to the under side-of thecover I25. :'I'here' is no' contact between the*sides,- ends,*orbottomQoi'cthis inner "shell I21 and thesides, ends 'or bottcm of 46-the' outer shell and. saidinner. shell ls absolutely hollow. V V I Oneend I20 of the inner shell has a circular opening I20 therein and amicrophone structure I30 is attached to said endover said opening- '50 tThis microphone structure projects through an opening in the end wallI25 of the oute'rfshell and this projecting portion of the saidmicrophone is conflned in a separate end-chamber Ill formed on the endof the outer shell andacces- 55 sible by means of a detachable coverI32, so that access may be gained tothe microphone'for the purpose ofconnecting or disconnecting the wires leading thereto. These variouswir'es,-in practice, are carried through pipes to one wall Ill of 50 themicrophone chamber.

I havefound in practice that it is 'quitedesirable to provide a secondcovering over the cover I26 of the shell because sound vibrations in theinner shell are so readily set up that a heavy rain, 65 or hail beatingdown directly on the cover I20 will cause vibrations atthe microphoneswhich will cause an operation of the signal mechanism. To

- avoidthis, I use a .rectangularshim I34 around 7 and cover so thatwhen rain or hail beat down on 75 the steel plate, there will be nodirect transmission of sound to the inner. shell.

A rectangular frame I31 is bolted through the marginal edges of thesaw-steel plate .tothe cover to hold the said plate in spaced relationabove the cover. w

It is, therefore,to be understood that each of the sound-producinghighway elements has the form of one hollow receptacle within another,and that each element is embedded in. the highw y. preferably with therectangular frame I31 flush with the upper highway surface, so that thewheels of a vehicle may pass overthe frame and the saw-steel platewithout jolt or jar to a vehicle or its occupants. 1

It is also to be understood-that there are no movable'parts or switchesthat have any movement as the result of actual contact with the vehiclewheels and, therefore, nothing to get out of order or requiring constantmaintenance as is the case where movable switch contacts are actuated bythe pasage of vehicles.

I claim:

l. A signal system for intersecting trafllc lanes having a right-of-waysignal indication for separate display to saidulanes; means actuated bytramc on one lane to display the right-of-way to that lane, and meansactuated by the sound of trafllc on the lane having the right-of-way formaintaining such right-of-way so long as such sound actuates the lastsaid means.

2. A. signal system for intersecting trafllc lanes having a right-of-waysignal indication for separate display to said lanes, means actuated byI trafllc passing in said lanes to transfer right of way back and forthbetween said lanes, and means actuated by thesound oftrailic on the lanehaving the right-of-way for maintaining such right-of-way so long assuch sound actuates the last said means.

wayfback and forth between said lanes, said means comprising soundactuated devices, and means actuated by the sound of traffic on the lanehaving the right-of-way for maintaining such right-of-way so long assuch sound actuates the last said means.

4. A signal system for intersecting trafllc lanes having a right-of-waysignal indication for sepa- .rate display to said lanes, means actuatedby having a right-of-way signal indication for separate display to saidlanes, means actuated by trafllc passing in said lanes to transferright-ofway back and forth between said lanes, said means comprisingsound actuated devices disposed in said lanes, and separate meansactuated l0 3 by the sound of trafllc on the lane having theright-of-way for maintaining such right-of-way so long as such soundactuates the last said means.

6. A signal system for intersecting tramc lanes having a right-of-waysignal indicationfor sepa- 1 rate display to said lanes, means actuatedby traillc on one lane to display the right-of-way to that lane, meansactuated by the sound of traffic on the lane having the right-of-way formainthat lane, means actuated by the sound of tramc 40 on the lanehaving the right-of-way for maintaining such right-of-way so long assuch sound actuates the last said means, and means-operated bytrafllctin another lane operable to transfer right-of-way to that lanebut subordinate to said last named sound actuated means.

CHARLES ADLER, JR.

